Process kit for RF physical vapor deposition

ABSTRACT

Embodiments of the invention generally relate to a process kit for a semiconductor processing chamber, and a semiconductor processing chamber having a kit. More specifically, embodiments described herein relate to a process kit including a cover ring, a shield, and an isolator for use in a physical deposition chamber. The components of the process kit work alone and in combination to significantly reduce particle generation and stray plasmas. In comparison with existing multiple part shields, which provide an extended RF return path contributing to RF harmonics causing stray plasma outside the process cavity, the components of the process kit reduce the RF return path thus providing improved plasma containment in the interior processing region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 12/433,315, filed Apr. 30, 2009, which claims benefit of U.S.Provisional Patent Application Ser. No. 61/050,112, filed May 2, 2008,all of which are hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention generally relate to a process kit for asemiconductor processing chamber, and a semiconductor processing chamberhaving a kit. More specifically, embodiments of the invention relate toa process kit including a cover ring, a shield, and isolator for use ina physical deposition chamber.

2. Description of the Related Art

Physical vapor deposition (PVD), or sputtering, is one of the mostcommonly used processes in the fabrication of electronic devices. PVD isa plasma process performed in a vacuum chamber where a negatively biasedtarget is exposed to a plasma of an inert gas having relatively heavyatoms (e.g., argon (Ar)) or a gas mixture comprising such inert gas.Bombardment of the target by ions of the inert gas results in ejectionof atoms of the target material. The ejected atoms accumulate as adeposited film on a substrate placed on a substrate support pedestaldisposed within the chamber.

A process kit may be disposed in the chamber to help define a processingregion in a desired region within the chamber with respect to thesubstrate. The process kit typically includes a cover ring, a depositionring, and a ground shield. Confining the plasma and the ejected atoms tothe processing region helps maintain other components in the chamberfree from deposited materials and promotes more efficient use of targetmaterials, as a higher percentage of the ejected atoms are deposited onthe substrate.

Although conventional ring and shield designs have a robust processinghistory, the reduction in critical dimensions brings increasingattention to contamination sources within the chamber. As the rings andshield periodically contact each other as the substrate support pedestalraises and lowers between transfer and process positions, conventionaldesigns are potential source of particulate contamination. Further,existing shield designs often lack multiple grounding points and areoften unable to provide the necessary electrical isolation to preventarcing from RF source plasma.

The deposition ring additionally prevents deposition on the perimeter ofthe substrate support pedestal. The cover ring is generally used tocreate a labyrinth gap between the deposition ring and ground shield,thereby preventing deposition below the substrate. The cover ring alsomay be utilized to assist in controlling deposition at or below thesubstrate's edge. Thus, the inventors have realized that is would beadvantageous to have a process kit that reduced stray plasma while alsominimizing chamber contamination.

Therefore, there is a need in the art for an improved process kit.

SUMMARY OF THE INVENTION

Embodiments of the invention generally provide a process kit for use ina physical vapor deposition (PVD) chamber and a PVD chamber having aninterleaving process kit. In one embodiment, the process kit includes aninterleaving ground shield, cover ring, and isolator ring.

In one embodiment, a shield for encircling a sputtering surface of asputtering target that faces a substrate support in a substrateprocessing chamber is provided. The shield comprises a cylindrical outerband having a first diameter sized to encircle the sputtering surface ofthe sputtering target. The cylindrical outer band has a top end sized tosurround the sputtering surface and a bottom end sized to surround thesubstrate support. A sloped step having a second diameter greater thanthe first diameter extends radially outward from the top end of thecylindrical outer band. A mounting flange extends radially outward fromthe sloped step. A base plate extends radially inward from the bottomend of the cylindrical outer band. A cylindrical inner bad is coupledwith the base plate and sized to encircle a peripheral edge of thesubstrate support.

In another embodiment, a cover ring for placement about a depositionring in a substrate processing chamber is provided. The deposition ringis positioned between a substrate support and a cylindrical shield inthe chamber. The cover ring comprises an annular wedge. The annularwedge comprises an inclined top surface encircling the substratesupport, the inclined top surface having an inner periphery and an outerperiphery. A footing extends downward from the inclined top surface torest on the deposition ring. A projecting brim extends about the innerperiphery of the top surface. An inner cylindrical band and an outercylindrical band extend downward from the annular wedge, the inner bandhaving a smaller height than the outer band.

In yet another embodiment, an isolator ring for placement between atarget and a ground shield is provided. The isolator ring comprises anannular band sized to extend about and surround a sputtering surface ofthe target. The annular band comprises a top wall having a first width,a bottom wall having a second width, and a support rim having a thirdwidth and extending radially outward from the top wall. A verticaltrench is formed between an outer periphery of the bottom wall and abottom contact surface of the support rim.

In yet another embodiment, a process kit for placement about asputtering target and a substrate support in a substrate processingchamber is provided. The process kit comprises a shield encircling thesputtering target and a substrate support. The shield comprises acylindrical outer band having a first diameter sized to encircle thesputtering surface of the sputtering target. The cylindrical outer bandhas a top end that surrounds the sputtering surface and a bottom endthat surrounds the substrate support. A sloped step having a seconddiameter greater than the first diameter extends radially outward fromthe top end of the cylindrical outer band. A mounting flange extendsradially outward from the sloped step. A base plate extends radiallyinward from the bottom end of the cylindrical band. A cylindrical innerband coupled with the base plate partially surrounds a peripheral edgeof the substrate support. The process kit further comprises an isolatorring. The isolator ring comprises an annular band extending about andsurrounds a sputtering surface of the target. The annular band comprisesa top wall having a first width, a bottom wall having a second width,and a support rim having a third width and extending radially outwardfrom the top wall. A vertical trench is formed between an outerperiphery of the bottom wall and a bottom contact surface of the supportrim.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a simplified sectional view of a semiconductor processingsystem having one embodiment of a process kit;

FIG. 2 is a partial sectional view of one embodiment of a process kitinterfaced with a target and adapter of FIG. 1;

FIG. 3 is a partial sectional view of one embodiment of a process kitinterfaced with a target and adapter of FIG. 1;

FIG. 4 is a partial sectional view of one embodiment of a process kitinterfaced with the processing system of FIG. 1;

FIG. 5A is a top view of a one piece shield according to an embodimentdescribed herein;

FIG. 5B is a side view of an embodiment of the one piece shield of FIG.5A;

FIG. 5C is a cross-section view of one embodiment of the one pieceshield of FIG. 5A;

FIG. 5D is a bottom view of one embodiment of the one piece shield ofFIG. 5A;

FIG. 6A is a top view of an insulator ring according to an embodimentdescribed herein;

FIG. 6B is a side view of one embodiment of the insulator ring of FIG.6A;

FIG. 6C is a cross-section view of one embodiment of the insulator ringof FIG. 6A; and

FIG. 6D is a bottom view of one embodiment of the insulator ring of FIG.6A.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

Embodiments of the invention generally provide a process kit for use ina physical deposition chamber (PVD) chamber. In one embodiment, theprocess kit provides a reduced RF return path contributing to areduction in RF harmonics and stray plasma outside the process cavity,which promotes greater process uniformity and repeatability along withlonger chamber component service life. In one embodiment, the processkit provides an isolator ring designed to reduce electrical shortsbetween the chamber walls and the target.

FIG. 1 depicts an exemplary semiconductor processing chamber 100 havingone embodiment of a process kit 150 capable of processing a substrate105. The process kit 150 includes a one-piece ground shield 160, aninterleaving cover ring 170, and an isolator ring 180. In the versionshown, the processing chamber 100 comprises a sputtering chamber, alsocalled a physical vapor deposition or PVD chamber, capable of depositingtitanium or aluminum oxide on a substrate. The processing chamber 100may also be used for other purposes, such as for example, to depositaluminum, copper, tantalum, tantalum nitride, tantalum carbide,tungsten, tungsten nitride, lanthanum, lanthanum oxides, and titanium.One example of a processing chamber that may be adapted to benefit fromthe invention is the ALPS® Plus and SIP ENCORE® PVD processing chamber,available from Applied Materials, Inc. of Santa Clara, Calif. It iscontemplated that other processing chambers including those from othermanufacturers may be adapted to benefit from the invention.

The processing chamber 100 includes a chamber body 101 having enclosurewalls 102 and sidewalls 104, a bottom wall 106, and a lid assembly 108that enclose an interior volume 110 or plasma zone. The chamber body 101is typically fabricated from welded plates of stainless steel or aunitary block of aluminum. In one embodiment, the sidewalls comprisealuminum and the bottom wall comprises stainless steel. The sidewalls104 generally contain a slit valve (not shown) to provide for entry andegress of a substrate 105 from the processing chamber 100. The lidassembly 108 of the processing chamber 100 in cooperation with theground shield 160 that interleaves with the cover ring 170 confines aplasma formed in the interior volume 110 to the region above thesubstrate.

A pedestal assembly 120 is supported from the bottom wall 106 of thechamber 100. The pedestal assembly 120 supports a deposition ring 302along with the substrate 105 during processing. The pedestal assembly120 is coupled to the bottom wall 106 of the chamber 100 by a liftmechanism 122 that is configured to move the pedestal assembly 120between an upper and lower position. Additionally, in the lowerposition, lift pins are moved through the pedestal assembly 120 to spacethe substrate from the pedestal assembly 120 to facilitate exchange ofthe substrate with a wafer transfer mechanism disposed exterior to theprocessing chamber 100, such as a single blade robot (not shown). Abellows 124 is typically disposed between the pedestal assembly 120 andthe chamber bottom wall 106 to isolate the interior volume 110 of thechamber body 101 from the interior of the pedestal assembly 120 and theexterior of the chamber.

The pedestal assembly 120 generally includes a substrate support 126sealingly coupled to a platform housing 128. The platform housing 128 istypically fabricated from a metallic material such as stainless steel oraluminum. A cooling plate (not shown) is generally disposed within theplatform housing 128 to thermally regulate the substrate support 126.One pedestal assembly 120 that may be adapted to benefit from theembodiments described herein is described in U.S. Pat. No. 5,507,499,issued Apr. 16, 1996 to Davenport et al., which is incorporated hereinby reference in its entirety.

The substrate support 126 may be comprised of aluminum or ceramic. Thesubstrate support 126 has a substrate receiving surface 127 thatreceives and supports the substrate 105 during processing, the surface127 having a plane substantially parallel to a sputtering surface 133 ofthe target 132. The support 126 also has a peripheral edge 129 thatterminates before an overhanging edge of the substrate 105. Thesubstrate support 126 may be an electrostatic chuck, a ceramic body, aheater or a combination thereof. In one embodiment, the substratesupport 126 is an electrostatic chuck that includes a dielectric bodyhaving a conductive layer embedded therein. The dielectric body istypically fabricated from a high thermal conductivity dielectricmaterial such as pyrolytic boron nitride, aluminum nitride, siliconnitride, alumina or an equivalent material.

The lid assembly 108 generally includes a lid 130, a target 132, and amagnetron 134. The lid 130 is supported by the sidewalls 104 when in aclosed position, as shown in FIG. 1. A ceramic ring seal 136 is disposedbetween the isolator ring 180 and the lid 130 and sidewalls 104 toprevent vacuum leakage therebetween.

The target 132 is coupled to the lid 130 and exposed to the interiorvolume 110 of the processing chamber 100. The target 132 providesmaterial which is deposited on the substrate during a PVD process. Theisolator ring 180 is disposed between the target 132, lid 130, andchamber body 101 to electrically isolate the target 132 from the lid 130and the chamber body 101.

The target 132 is biased relative to ground, e.g. the chamber body 101and adapters 220, by a power source 140. A gas, such as argon, issupplied to the interior volume 110 from a gas source 142 via conduits144. The gas source 142 may comprise a non-reactive gas such as argon orxenon, which is capable of energetically impinging upon and sputteringmaterial from the target 132. The gas source 142 may also include areactive gas, such as one or more of an oxygen-containing gas, anitrogen-containing gas, a methane-containing gas, that are capable ofreacting with the sputtering material to form a layer on a substrate.Spent process gas and byproducts are exhausted from the chamber 100through exhaust ports 146 that receive spent process gas and direct thespent process gas to an exhaust conduit 148 having a throttle valve tocontrol the pressure of the gas in the chamber 100. The exhaust conduit148 is connected to one or more exhaust pumps 149. Typically, thepressure of the sputtering gas in the chamber 100 is set tosub-atmospheric levels, such as a vacuum environment, for example, gaspressures of 0.6 mTorr to 400 mTorr. A plasma is formed between thesubstrate 105 and the target 132 from the gas. Ions within the plasmaare accelerated toward the target 132 and cause material to becomedislodged from the target 132. The dislodged target material isdeposited on the substrate.

The magnetron 134 is coupled to the lid 130 on the exterior of theprocessing chamber 100. One magnetron which may be utilized is describedin U.S. Pat. No. 5,953,827, issued Sep. 21, 1999 to Or et al., which ishereby incorporated by reference in its entirety.

The chamber 100 is controlled by a controller 190 that comprises programcode having instruction sets to operate components of the chamber 100 toprocess substrates in the chamber 100. For example, the controller 190can comprise program code that includes a substrate positioninginstruction set to operate the pedestal assembly 120; a gas flow controlinstruction set to operate gas flow control valves to set a flow ofsputtering gas to the chamber 100; a gas pressure control instructionset to operate a throttle valve to maintain a pressure in the chamber100; a temperature control instruction set to control a temperaturecontrol system (not shown) in the pedestal assembly 120 or sidewall 104to set temperatures of the substrate or sidewalls 104, respectively; anda process monitoring instruction set to monitor the process in thechamber 100.

The chamber 100 also contains a process kit 150 which comprises variouscomponents that can be easily removed from the chamber 100, for example,to clean sputtering deposits off the component surfaces, replace orrepair eroded components, or to adapt the chamber 100 for otherprocesses. In one embodiment, the process kit 150 comprises an isolator180, a ground shield 160 and a ring assembly 168 for placement about aperipheral edge 129 of the substrate support 126 that terminates beforean overhanging edge of the substrate 105.

The shield 160 encircles the sputtering surface 133 of a sputteringtarget 132 that faces the substrate support 126 and the peripheral edge129 of the substrate support 126. The shield 160 covers and shadows thesidewalls 104 of the chamber 100 to reduce deposition of sputteringdeposits originating from the sputtering surface 133 of the sputteringtarget 132 onto the components and surfaces behind the shield 160. Forexample, the shield 160 can protect the surfaces of the support 126, theoverhanging edge of the substrate 105, sidewalls 104 and bottom wall 106of the chamber 100.

As shown in FIGS. 1, 5A, 5B, 5C, and 5D, the shield 160 is of unitaryconstruction and comprises a cylindrical outer band 210 having adiameter dimensioned to encircle the sputtering surface 133 of thesputtering target 132 and the substrate support 126. In one embodiment,the cylindrical outer band 210 has an inner diameter represented byarrows “A”. In one embodiment, the inner diameter “A” of the cylindricalouter band 210 is between about 16 inches (40.6 cm) and about 18 inches(45.7 cm). In another embodiment, the inner diameter “A” of thecylindrical outer band 210 is between about 16.8 inches (42.7 cm) andabout 17 inches (43.2 cm). In one embodiment, the cylindrical outer band210 has an outer diameter represented by arrows “B”. In one embodiment,the outer diameter “B” of the cylindrical outer band 210 is betweenabout 17 inches (43.2 cm) and about 19 inches (48.3 cm). In anotherembodiment, the outer diameter “B” of the cylindrical outer band 210 isbetween about 17.1 inches (43.4 cm) and about 17.3 inches (43.9 cm).

The cylindrical outer band 210 has a top end 212 that surrounds thesputtering surface 133 of the sputtering target 132 and a bottom end 213that surrounds the substrate support 126. A sloped step 214 extendsradially outward from the top end 212 of the cylindrical outer band 210.In one embodiment, the sloped step 214 forms an angle “α” relative tovertical. In one embodiment, the angle “α” is from between about 15degrees to about 25 degrees from vertical. In another embodiment, thesloped angle “α” is about 20 degrees.

In one embodiment, the shield 160 has a height “C” between about 10inches and about 12 inches. In another embodiment, the shield 160 has aheight “C” between about 11 inches (27.9 cm) and 11.5 inches (29.2 cm).In yet another embodiment, the shield 160 has a height “C” between about7 inches (17.8 cm) and about 8 inches (20.3 cm). In yet anotherembodiment, the shield has a height “C” between about 7.2 inches (18.3cm) and about 7.4 (18.8 cm).

A mounting flange 216 extends radially outward from the sloped step 214of the cylindrical outer band 210. Referring to FIG. 2 and FIG. 5C, themounting flange 216 comprises a lower contact surface 218 to rest uponan annular adapter 220 surrounding the sidewalls 104 of the chamber 100and an upper contact surface 219. In one embodiment, the lower contactsurface 218 of the mounting flange 216 comprises a plurality ofcounterbores (not shown) shaped and sized to receive a screw to affixthe shield 160 to the adapter 220. As shown in FIG. 2, an innerperiphery 217 of the upper contact surface 219 forms a step 221. Thestep 221 provides a labyrinth gap that prevents conductive material fromcreating a surface bridge between the isolator ring 180 and the shield160, thus maintaining electrical discontinuity.

In one embodiment, the adapter 220 supports the shield 160 and can serveas a heat exchanger about the sidewall 104 of the substrate processingchamber 100. The adapter 220 and the shield 160 form an assembly thatallows improved heat transfer from the shield 160 and which reducesthermal expansion stresses on the material deposited on the shield.Portions of the shield 160 can become excessively heated by exposure tothe plasma formed in the substrate processing chamber 100, resulting inthermal expansion of the shield and causing sputtering deposits formedon the shield to flake off from the shield and fall upon and contaminatethe substrate 105. The adapter 220 has a resting surface 222 thatcontacts the lower contact surface 218 of the shield 160 to allow goodelectrical and thermal conductivity between the shield 160 and theadapter 220. In one embodiment, the adapter 220 further comprisesconduits for flowing a heat transfer fluid therethrough to control thetemperature of the adapter 220.

Referring to FIGS. 1, 4, 5A, 5B, 5C, and 5D, the cylindrical outer band210 also comprises a bottom end 213 that surrounds the substrate support126. A base plate 224 extends radially inward from the bottom end 213 ofthe cylindrical outer band 210. A cylindrical inner band 226 is coupledwith the base plate 224 and at least partially surrounding theperipheral edge 129 of the substrate support 126. In one embodiment, thecylindrical inner band has a diameter represented by arrows “D”. In oneembodiment, the cylindrical inner band 226 has a diameter “D” betweenabout 14 inches (35.6 cm) and about 16 inches (40.6 cm). In anotherembodiment, the cylindrical inner band 226 has a diameter “D” betweenabout 14.5 inches (36.8 cm) and about 15 inches (38.1 cm). Thecylindrical inner band 226 extends upward from and is perpendicular tothe base plate 224. The cylindrical inner band 226, the base plate 224,and the cylindrical outer band 210 form a U-shaped channel. Thecylindrical inner band 226 comprises a height that is less than theheight of the cylindrical outer band 210. In one embodiment, the heightof the inner band 226 is about one fifth of the height of thecylindrical outer band 210. In one embodiment, the cylindrical innerband 226 has a height represented by arrows “E”. In one embodiment, theheight “E” of the cylindrical inner band 226 is from about 0.8 inches (2cm) to about 1.3 inches (3.3 cm). In another embodiment, the height “E”of the cylindrical inner band 226 is from about 1.1 inches (2.8 cm) toabout 1.3 inches (3.3 cm). In another embodiment, the height of thecylindrical inner band 226 is from about 0.8 inches (2 cm) to about 0.9inches (2.3 cm).

The cylindrical outer band 210, the sloped step 214, the mounting flange216, the base plate 224, and the cylindrical inner band 226 comprise aunitary structure. For example, in one embodiment, the entire shield 160can be made from aluminum or in another embodiment, 300 series stainlesssteel. A unitary shield 160 is advantageous over prior shields whichincluded multiple components, often two or three separate pieces to makeup the complete shield. In comparison with existing multiple partshields, which provide an extended RF return path contributing to RFharmonics causing stray plasma outside the process cavity, the unitaryshield reduces the RF return path thus providing improved plasmacontainment in the interior processing region. A shield 160 withmultiple components makes it more difficult and laborious to remove theshield for cleaning. The single piece shield 160 has a continuoussurface exposed to the sputtering deposits without interfaces or cornersthat are more difficult to clean out. The single piece shield 160 alsomore effectively shields the chamber walls 104 from sputter depositionduring process cycles. In one embodiment, conductance features, such asconductance holes, are eliminated. The elimination of conductancefeatures reduces the formation of stray plasmas outside of the interiorvolume 110.

In one embodiment, the exposed surfaces of the shield 160 are treatedwith CLEANCOAT™, which is commercially available from Applied Materials,Santa Clara, Calif. CLEANCOAT™ is a twin-wire aluminum arc spray coatingthat is applied to substrate processing chamber components, such as theshield 160, to reduce particle shedding of deposits on the shield 160and thus prevent contamination of a substrate 105 in the chamber 100. Inone embodiment, the twin-wire aluminum arc spray coating on the shield160 has a surface roughness of from about 600 to about 2300 microinches.

The shield 160 has exposed surfaces facing the interior volume 110 inthe chamber 100. In one embodiment, the exposed surfaces are beadblasted to have a surface roughness of 175±75 microinches. Thetexturized bead blasted surfaces serve to reduce particle shedding andprevent contamination within the chamber 100. The surface roughnessaverage is the mean of the absolute values of the displacements from themean line of the peaks and valleys of the roughness features along theexposed surface. The roughness average, skewness, or other propertiesmay be determined by a profilometer that passes a needle over theexposed surface and generates a trace of the fluctuations of the heightof the asperities on the surface, or by a scanning electron microscopethat uses an electron beam reflected from the surface to generate animage of the surface.

Referring to FIG. 3, in one embodiment, the isolator ring 180 isL-shaped. The isolator ring 180 comprises an annular band that extendsabout and surrounds the sputtering surface 133 of the target 132. Theisolator ring 180 electrically isolates and separates the target 132from the shield 160 and is typically formed from a dielectric orinsulative material such as aluminum oxide. The isolator ring 180comprises a lower horizontal portion 232 and a vertical portion 234extending upward from the lower horizontal portion 232. The lowerhorizontal portion 232 comprises an inner periphery 235, an outerperiphery 236, a bottom contact surface 237, and top surface 238,wherein the bottom contact surface 237 of the lower horizontal portion232 contacts an upper contact surface 219 of the mounting flange 216. Inone embodiment the upper contact surface 219 of the shield 160 forms astep 221. The step 221 provides a labyrinth gap that prevents conductivematerial from creating a surface bridge between the isolator ring 180and the shield 160, thus maintaining electrical discontinuity. The uppervertical portion 234 of the isolator ring 180 comprises an innerperiphery 239, an outer periphery 240, and a top surface 241. The innerperiphery 239 of the upper vertical portion 234 and the inner periphery235 of the lower horizontal portion 232 form a unitary surface. The topsurface 238 of the lower horizontal portion 232 and the outer periphery240 of the upper vertical portion 234 intersect at a transition point242 to form a step 243. In one embodiment, the step 243 forms alabyrinth gap with the ring seal 136 and target 132.

In one embodiment, the isolator ring 180 has an inner diameter, definedby inner periphery 235 and inner periphery 239, between about 17.5inches (44.5 cm) and about 18 inches (45.7 cm). In another embodiment,the isolator ring 180 has an inner diameter between about 17.5 inches(44.5 cm) and 17.7 inches (45 cm). In one embodiment, the isolator ring180 has an outer diameter, defined by the outer periphery 236 of thelower horizontal portion 232, between about 18 inches (45.7 cm) andabout 19 inches (48.3 cm). In another embodiment, the isolator ring 180has an outer diameter between about 18.7 inches (47.5 cm) and about 19inches (48.3 cm). In another embodiment, the isolator ring 180 has asecond outer diameter, defined by the outer periphery 240 of the uppervertical portion 234, between about 18 inches (45.7 cm) and about 18.5inches (47 cm). In another embodiment, the second outer diameter isbetween about 18.2 inches (46.2 cm) and about 18.4 inches (46.7 cm). Inone embodiment, the isolator ring 180 has a height between about 1 inch(2.5 cm) and about 1.5 inches (3.8 cm). In another embodiment, theisolator ring 180 has a height between about 1.4 inches (3.6 cm) andabout 1.45 inches (3.7 cm).

In one embodiment, the exposed surfaces, including the top surface 241and inner periphery of the vertical portion 234, the inner periphery 235and bottom contact surface 237 of the lower horizontal portion 232 ofthe isolator 180 are textured using for example, grit blasting, with asurface roughness of 180±20 Ra, which provides a suitable texture forlow deposition and lower stress films.

With reference to FIGS. 2, 6A, 6B, 6C, and 6D in another embodiment, theisolator ring 280 is T-shaped. The isolator ring 280 comprises anannular band 250 that extends about and surrounds the sputtering surface133 of the target 132. The annular band 250 of the isolator ring 280comprises a top wall 252 having a first width, a bottom wall 254 havinga second width, and a support rim 256, having a third width, extendingradially outward from the top wall 252 of the annular band 250. In oneembodiment, the first width is less than the third width but greaterthan the second width. In one embodiment, the isolator ring 280 has anouter diameter “F” of between about 18.5 inches (47 cm) and about 19inches (48.3 cm). In another embodiment, the isolator ring 280 has anouter diameter “F” of between about 18.8 inches (47.8 cm) and about 18.9inches (48 cm).

The top wall 252 comprises an inner periphery 258, a top surface 260positioned adjacent to the target 132, and an outer periphery 262positioned adjacent to the ring seal 136. The support rim 256 comprisesa bottom contact surface 264 and an upper surface 266. The bottomcontact surface 264 of the support rim 256 rests on an aluminum ring267. In certain embodiments, the aluminum ring 267 is not present andthe adapter 220 is configured to support the support rim 256. The bottomwall 254 comprises an inner periphery 268, an outer periphery 270, and abottom surface 272. The inner periphery 268 of the bottom wall 254 andthe inner periphery 258 of the top wall 252 form a unitary surface. Inone embodiment, the isolator ring 280 has an inner diameter “G”, definedby the inner periphery 268 of the bottom wall 254 and the innerperiphery 258 of the top wall 252, between about 17 inches (43.2 cm) andabout 18 inches (45.7 cm). In another embodiment, the inner diameter “G”of the isolator ring 280 is between about 17.5 inches (44.5 cm) andabout 17.8 inches (45.2 cm).

A vertical trench 276 is formed at a transition point 278 between theouter periphery 270 of the bottom wall 254 and the bottom contactsurface 264 of the support rim 256. The step 221 of the shield 160 incombination with the vertical trench 276 provides a labyrinth gap thatprevents conductive material from creating a surface bridge between theisolator ring 280 and the shield 160, thus maintaining electricaldiscontinuity while still providing shielding to the chamber walls 104.In one embodiment, the isolator ring 280 provides a gap between thetarget 132 and the ground components of the process kit 150 while stillproviding shielding to the chamber walls. In one embodiment, the gapbetween the target 132 and the shield 160 is between about 1 inch (2.5cm) and about 2 inches (5.1 cm), for example, about 1 inch (2.5 cm). Inanother embodiment, the gap between the target 132 and the shield 160 isbetween about 1.1 inches (2.8 cm) and about 1.2 inches (3 cm). In yetanother embodiment the gap between the target 132 and the shield 160 isgreater than 1 inch (2.5 cm). The stepped design of the isolator ring280 allows for the shield 160 to be centered with respect to the adapter220, which is also the mounting point for the mating shields and thealignment features for the target 132. The stepped design alsoeliminates line-of-site from the target 132 to the shield 160,eliminating stray plasma concerns in this area.

In one embodiment, the isolator ring 280 has a grit-blasted surfacetexture for enhanced film adherence with a surface roughness of 180±20Ra, which provides a suitable texture for low deposition and lowerstress films. In one embodiment, the isolator ring 280 has a surfacetexture provided through laser pulsing for enhanced film adherence witha surface roughness of >500 Ra for a higher deposition thickness andhigher film stress. In one embodiment, the textured surfaces extend thelifetime of the isolator ring 280 when the processing chamber 100 isused to deposit metals, metal nitrides, metal oxides, and metalcarbides. The isolator ring 280 is also removable from the chamber 100providing the ability to recycle the part without impact on materialporosity that would prevent reuse in a vacuum seal application. Thesupport rim 256 allows for the isolator ring 280 to be centered withrespect to the adapter 220 while eliminating the line-of-site from thetarget 132 to the ground shield 160 thus eliminating stray plasmaconcerns. In one embodiment the ring 267 comprises a series of alignmentpins (not shown) that locate/align with a series of slots (not shown) inthe shield 160.

Referring to FIG. 4, the ring assembly 168 comprises a deposition ring302 and a cover ring 170. The deposition ring 302 comprises an annularband 304 surrounding the support 126. The cover ring 170 at leastpartially covers the deposition ring 302. The deposition ring 302 andthe cover ring 170 cooperate with one another to reduce formation ofsputter deposits on the peripheral edges 129 of the support 126 and theoverhanging edge of the substrate 105.

The cover ring 170 encircles and at least partially covers thedeposition ring 302 to receive, and thus, shadow the deposition ring 302from the bulk of the sputtering deposits. The cover ring 170 isfabricated from a material that can resist erosion by the sputteringplasma, for example, a metallic material such as stainless steel,titanium or aluminum, or a ceramic material, such as aluminum oxide. Inone embodiment, the cover ring 170 is composed of titanium having apurity of at least about 99.9 percent. In one embodiment, a surface ofthe cover ring 170 is treated with a twin-wire aluminum arc-spraycoating, such as, for example, CLEANCOAT™, to reduce particle sheddingfrom the surface of the cover ring 170.

The cover ring 170 comprises an annular wedge 310 comprising an inclinedtop surface 312 that is sloped radially inwards and encircles thesubstrate support 126. The inclined top surface 312 of the annular wedge310 has an inner periphery 314 and an outer periphery 316. The innerperiphery 314 comprises a projecting brim 318 which overlies theradially inward dip comprising an open inner channel of the depositionring 302. The projecting brim 318 reduces deposition of sputteringdeposits on the open inner channel of the deposition ring 302. In oneembodiment, the projecting brim 318 projects a distance corresponding toat least about half the width of an arc-shaped gap 402 formed with thedeposition ring 302. The projecting brim 318 is sized, shaped, andpositioned to cooperate with and complement the arc-shaped gap 402 toform a convoluted and constricted flow path between the cover ring 170and deposition ring 302 that inhibits the flow of process deposits ontothe substrate support 126 and the platform housing 128. The constrictedflow path of the gap 402 restricts the build-up of low-energy sputterdeposits on the mating surfaces of the deposition ring 302 and the coverring 170, which would otherwise cause them to stick to one another or tothe peripheral overhanging edge of the substrate 105.

The inclined top surface 312 may be inclined at an angle of betweenabout 10 degrees and about 20 degrees, for example, about 16 degreesfrom horizontal. The angle of the inclined top surface 312 of the coverring 170 is designed to minimize the buildup of sputter deposits nearestto the overhanging edge of the substrate 105, which would otherwisenegatively impact the particle performance obtained across the substrate105.

The cover ring 170 comprises a footing 320 extending downward from theinclined top surface 312 of the annular wedge 310, to rest upon a ledge306 of the deposition ring 302. The footing 320 extends downwardly fromthe wedge 310 to press against the deposition ring 302 substantiallywithout cracking or fracturing the ring 302. In one embodiment, adual-stepped surface is formed between the footing 320 and a lowersurface of the projecting brim 318.

The cover ring 170 further comprises an inner cylindrical band 324 a andan outer cylindrical band 324 b that extend downwardly from the annularwedge 310, with a gap therebetween. In one embodiment, the innercylindrical band 324 a and the outer cylindrical band 324 b aresubstantially vertical. The inner and outer cylindrical bands 324 a and324 b are located radially outward of the footing 320 of the annularwedge 310. The inner cylindrical band 324 a has a height that is smallerthan the outer cylindrical band 324 b. Typically, the height of theouter cylindrical band 324 b is at least about 1.2 times the height ofthe inner cylindrical band 324 a. For example, for a cover ring 170having an inner radius of about 154 mm, the height of the outercylindrical band 324 b is from about 15 to about 35, or example, 25 mm;and the height of the inner cylindrical band 324 a is from about 12 toabout 24 mm, for example, about 19 mm. The cover ring may comprise anymaterial that is compatible with process chemistries such as titanium orstainless steel.

In one embodiment, a surface of the inner cylindrical band 324 a isangled between about 12 degrees and about 18 degrees from vertical. Inanother embodiment, the surface of the inner cylindrical band 324 a isangled between about 15 degrees and about 17 degrees.

In one embodiment, the cover ring 170 has an outer diameter, defined bythe outer cylindrical band 324 b, between about 15.5 inches (39.4 cm)and about 16 inches (40.6 cm). In another embodiment, the cover ring 170has an outer diameter between about 15.6 inches (39.6 cm) and about 15.8inches (40.1 cm). In one embodiment, the cover ring 170 has a heightbetween about 1 inch (2.5 cm) and about 1.5 inches (3.8 cm). In anotherembodiment, the cover ring 170 is between about 1.2 inches (3 cm) andabout 1.3 inches (3.3 cm).

The space or gap 404 between the shield 160 and the cover ring 170 formsa convoluted S-shaped pathway or labyrinth for plasma to travel. Theshape of the pathway is advantageous, for example, because it hindersand impedes ingress of plasma species into this region, reducingundesirable deposition of sputtered material.

The components of the process kit 150 described work alone and incombination to significantly reduce particle generation and strayplasmas. In comparison with existing multiple part shields, whichprovided an extended RF return path contributing to RF harmonics causingstray plasma outside the process cavity, the one piece shield describedabove reduces the RF return path thus providing improved plasmacontainment in the interior processing region. The flat base-plate ofthe one piece shield provides an additional shortened return path for RFthrough the pedestal to further reduce harmonics and stray plasma aswell as providing a landing for existing grounding hardware. The onepiece shield also eliminates all conductance features which provideddiscontinuities in RF return and led stray plasmas outside the processcavity. The one piece shield was modified to allow for insertion of anisolator ring into the process chamber. The isolator ring blocks theline of sight between the RF source and the process kit parts in theground path. The mounting flange on the shield was modified to provide astep and large radius which provide a labyrinth that prevents conductivematerial deposition from creating a surface bridge between the isolatorring and the shield thus maintaining electrical discontinuity. The onepiece shield is also designed for low-cost manufacturability throughreducing materials thickness in order to allow for manufacturing throughflow forming.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

The invention claimed is:
 1. A cover ring for placement about adeposition ring in a substrate processing chamber, wherein thedeposition ring is adapted to be positioned between a substrate supportand a cylindrical shield in the chamber, the cover ring comprising: anannular wedge comprising: an inclined top surface sized to encircle thesubstrate support, the inclined top surface having an inner peripheryand an outer periphery; a footing extending downward from the inclinedtop surface and configured to rest on the deposition ring; and a roundedprojecting brim about the inner periphery of the inclined top surface,wherein a dual-stepped surface is formed by an arc-shaped gap oppositethe inclined top surface between the footing and a lower surface of theprojecting brim; an inner cylindrical band extending downward from theannular wedge; and an outer cylindrical band extending downward from theannular wedge, wherein the inner cylindrical band has a height smallerthan a height of the outer cylindrical band, wherein the innercylindrical band and the outer cylindrical band are located radiallyoutward of the footing of the annular wedge and an outer periphery ofthe outer cylindrical band extends vertically upward to the outerperiphery of the inclined top surface.
 2. The covering ring of claim 1,wherein the cover ring comprises stainless steel.
 3. The cover ring ofclaim 1 wherein the inclined top surface of the annular wedge slopesradially inward.
 4. The cover ring of claim 1, wherein the innercylindrical band and the outer cylindrical band are substantiallyvertical.
 5. The cover ring of claim 1, comprising an exposed surfacehaving a twin-wire aluminum arc spray coating.
 6. The cover ring ofclaim 1, wherein the cover ring is fabricated from a metallic materialselected from the group consisting of: titanium or aluminum.
 7. Thecover ring of claim 6, wherein the cover ring is fabricated fromtitanium having a purity of at least about 99.9%.
 8. The cover ring ofclaim 1, wherein the projecting brim projects a distance correspondingto at least about half the width of the arc-shaped gap.
 9. The coverring of claim 1, wherein the inclined top surface is inclined at anangle of between about 10 degrees and about 20 degrees.
 10. The coverring of claim 1, wherein a surface of the inner cylindrical band thatfaces the deposition ring is angled between about 12 degrees and about18 degrees from vertical.